Evaporator



J. C. LAWRENCE EVAPORATOR Filed April 11 Patented Jan. 27, 1925.

PAT ENT ()FF ICE.

JAMES CUTHBERT LAWRENCE, OF SVVAR'IHMORE, PENNSYLVANIA.

' EVAPORATOB.

Application filed April 11, 1919. Serial No. 289,386;

To all whom it may concern.

Be it known that I, JAMES Cu'rnnnnr LAWRENCE, a citizen of the United States, residing at Swarthmore,-in the county of Delaware and State of Pennsylvania, have invented certain new and useful Improvements in Eviiiporators, of which the following is a specification.

This invention pertains to evaporators-of the so-called climbingfilm type, an example of which is illustrated and described in British Patent No. 715s of 1909, and the purpose of the present improvements is to secure a higher degree of concentration than heretofore without increasing the area of heating surface, or the temperature.

In the embodiment of this type of evaporator here illustrated a continuous upward flow of the liquid to be concentrated is effected by connecting the upper part of the apparatus with a condenser, and thus obtaining in such upper part a partial vacuum, so that the liquid is caused to ascend by reason of the pressure of the atmosphere acting upon its surface in the supply tank or reservoir; but it is to be understood that the How may be caused by placing the reservoir at proper elevation, by pumping, or otherwise.

It is also to be understood that the several heating and separating compartments which are here illustrated as arranged in alternation one above another, may if desired be arranged in separate chambers side-by side, suitable connection being made from one to the other.

T he present invention consists in dividing the lower part of the last or upper separating chamber into a plurality of sections or liquid containing compartments, separated by partition walls, and in connecting each compartment so formed, by a pipe or tube with the space beneath the tubes of the next compartment, until the final chamber is reached, which chamber is provided with a discharge or delivery pipe by which the concentrated liquid is delivered to a storage tank or receptacle. In this way the liquid undergoes in the final heating compartment, a longer travel and a greater number of separations of vapor and liquid or L condensate than under the former construction, and this in turn enables me to secure a higher degree of concentration.

The invention is illustrated in the accompanying drawings, in which:

Figure 1 is a vertical section on the line II of Fig. 2, through an apparatus com-'- prising'two heating compartin'ients and two separating chambers arranged progressively and in alternation one above another;

Figure 2, a similarsectional view of the upper heating compartment taken on the line II-II of Fig; 1;

Figure 3, a horizontal-secton on the line IIIIII of Fig. 2, portionsoi the floor and of the vapor pipe hoods of the upper separating compartment being broken away to show the tube sheet and tubcsbelow;

Figure 4, a perspective view partially broken away or in section, oi? the uppermost separating chamber, illustrating the manner of subdividing its lower or liquid-holding portion.

Except for the subdivision of the lower or liquid holding portion of the upper separating compartment, and for the discharge pipes for returning the liquid from each section or chamber to the lower ends of the tubes of a succeeding section or chamber, the structure may be identical with that of British Patent No. 7154 or 1909 above referred to, and in fact is here-so represented, but the invention may be carried. out in varied form provided the general plan of construction and mode of ope 'ation be retained.

In these drawings 1 indicates a shell or casing, which may conveniently be made of sheet or plate metal and of cylindrical form. Ths shell or casing, which is closed at its lower end, isprovided with cross partitions, diaphragms, or tube sheets 2 and 8, suitably spaced apart, and connected by tubes & after the manner oil a vertical tube boiler, the lower tube, sheet being a short distance above the bottom of the casing. At a short distance above the upper tube sheet 3 is another diaphragn'i or partition 5 of conical or centrally rascd term, and provided at its center with a tight fitting flaring pipe or funnel 6 passing through and extending both above and below the diaphragm or partition 5, as shown. ()verhging the upper end of the pipe or iunnel (3 is a concavo-convex hood or cover 7, the circumferential edge of which is spaced slightly above the corresponding edge of the tunnel 6, to produce a narrow slit or open ing on all sides. The space 37 between the tube sheet 3 and diaphragm or partition 5 constitutes a vapor chamber into which vapor formed through the heating of the liquid in the tubes enters.

Steam is introduced. into the heating compartment 8 by a suitable pipe 9 passing through the bot-tom of the shell or casing 1 and through the diaphragm or tube sheet 2.

A liquid supply pipe 10 opens into the space between the bottom of the shell or casing and diaphragm 2, and is provided with a closing valve 11 and a constriction 12, the latter being designed to regulate the continuous flow of liquid while the apparatus is in operation, and the valve serving completely to cut oil the flow of liquid when required.

Above the funnel 6 and hood 7 is a second heating compartment- 13 in all material respects like the compartment 8; that is to say, it comprises a bottom plate or partition 14, a short distance above which is a tube sheetor diaphragm 15, and at a suitable distance above this a second tube sheet 16,

said sheets being connected by tubes 17. The space 18 between the two heating compartments constitutes a separating chamber in which the liquid and vapor are separated, and from which the vapor passes to the upper compartment through a central pipe 19, while the liquid condensate occupies the base or lower pait of said chamber. The liquid space between the bottom plate 14. of compartment 13 and the lower tube plate 15 communicates with the separating chamber 18 by a depending pipe 20, the lower end of which approaches close to the conical )artition 5 at a oint near its circumference. P

so that its lower end shall be sealed by liquid lying above said partition. 'A constriction 21 is formed near the lower end of said pipe 20.

Abo'verthet-ube'sheet 16 is a transverse partition 22, which forms the bottom of a second separating chamber 23, the sidewalls and top of which are formed by the domeshaped top of the shell or casing 1. The space 38 between tube sheet 16 and partition 22 constitutes a second vapor chamber. Trisecting the diaphragm or partition 22 are vertical partitions 24 radial to the axis of the shell or casing, and rising from the tube sheet 16 to a point considerably above the level of the diaphragm or partition 22, thus dividing the lower or liquid-holding portion of separating chamber 28 into three sections or divisions 25, 26 and 27, as best shown in Figs. 3' and. 4. It will be observed that since the partitions 2% make close and liquid-tight-contact or connection with the tube sheet 16, the space between said tube sheet and the diaphragm or partition 22 is similarly divided into three sections or chambers, and since the tubes 17 open into these separate chambers or sections, the tubes are divided into three separate groups so far as their discharge is concerned, but they have a common heating means and communicate with a common liquid-supply chamber at their lower ends.

With-in each section or division of the liquid holding space of the separating chamber 23 produced by the partitions 24-, there is arranged a flaring pipe or tunnel 28 and hood 29 of the same form and construction as the funnel and hood (3 and 'i'. From the section or division a discharge pi pc ill). the upper end of which is raised slightl above diaphragm 22, pa downward through the upper and lower tube sheets 16 and 15 to the liquid space beneath thev latter, and this pipe 30 serves to convey to the liquid space beneath tube sheet 15 any liquid rising above the top of said pipe 30 in section or division of the separating chamber 23. The pipe is located, preferably, close to the partition separating sections 25 and 26 and near the outer shell or casing 1, so that liquid descending through it will be delivered close to and will flow into, the liquid space vertically below section 26. It will hence more or less mingle with the other contents of the liquid space below tube sheet 15, rise through the tubes 17 into the section 26 above tube sheet It and below diaphragm 22, and the vapor therefrom will ascend through the funnel 28 of section or division 26 and be discharged therein.

Similarly, a pipe 31 passes through partition 22 and tube sheets 15 and 10 to the liquid space below tube sheet 1:) at a point close to the tubes 17, commuuicating with section or division 27, the upper end ol said pipe 31 advisably rising slightly above said diaphragm or partition From the section or division 27 a discharge pipe 32 (Figs. 1 and 3), opens outward and descends to the reservoir or receptacle in which the concentrated liquid is to be stored.

The lower heating compartment 8 has direct communication with the upper heating compartment 13 by a pipe 33, the ends of which tap the heating compartments near their bottoms.

3 L indicates a vapor pipe which connects with a condenser oi any suitable type, to carry ofl' any uncondensed vapor which may accumulate in the dome or top of the shell or casing 1. This pipe 234 communicates by a smaller pipe or cross connection with the upper heating compartment 13, said pipe being provided with a constriction 36.

The constrictions in the several pipes 10.

V20, 33 and 35 are, as heretofore, provided for the purpose oi determining and controlling the circulation velocily, and the areas of the openings must be carefully determined or adjusted according to the desired llltl velocity of flow and other conditions, such as fall in temperature, pressure, etc, as is well understood. Cocks or valves may be employed to enable the area of these restricted passages to be varied as circum stances require.

It will be seen from the foregoing description that the evaporator comprises a plurality of heaters, arranged within a. common casing one above another, and that each heater comprises a series of tubes extending from a. lower to an upper tube sheet, the tubes communicating at their lower ends with a liquid space or feed chamber supplying and common to all the tubes, said chamber being without partitions of any kind. It will further be seen that the tubes of each heating chamber open into a vapor chamber, the top wall of which terms the floor of a separating chamber in which a portion of the vapor is condensed and in the base of which the liquid or condensate is collected. Finally, it will be noted that the vapor chamber and the separating chamber of the topmost heater of the series areboth divided by partitions into separate compartments, each compartment receiving vapor from a separate group of tubes of the final heater, and having its own separating funnel and hood.

The apparatus constructed as above and being connected wit-h a condenser or having the liquid supplied under suitable head or pressure, operates as'follows:

Liquid entering through pipe l0 fills the space beneath tube sheet 2, and rises within the tubes 4, to a greater or less height. Steam is at the same time introduced through pipe 9, and fills the heating compartment 8, encompassing tubes 4 and heating their contents sufficiently to cause vaporization thereof. This, owing'to connection with the condenser and the inainte nance of vacuum within the shell or casing 1, takes place at a relatively low temperature, and the vapor rising through the fun nel 6 blows out through the narrow slit or opening between the tunnel and its hood in the form of a thin curtain, being-projected against the side walls of the separating chamber 18 with considerable force. Coming into contact with the walls of chamber 18 the vapor is in considerable degree condensed, the condensate running down the walls of the chamber and accumulating in the base thereof above the partition 5, where it forms a seal to the lower end of pipe 20. Said pipe being'tlius sealed the liquid will by reason ofthe vacuum in the upper part of the shell or casing and the pressure on the liquid, be caused to How upward through the pipe 20, and thence through the pipes 17, in traversing which it is further heated, in part vaporized, and discharged in the term of vapor through the tunnels 28 into the respective sections or divisions 25, 26 and 27 of separating chamber 23. The liquid collecting in sec-- tion flows by gravity backto the space beneath tube sheet 15, and mingling with the liquid therein rises through the tubes 17, and mainly through those of section 26 because of its delivery at a point close to the tubes communicating with that section. tbimilarly, the liquid accumulating in section 26 descends through pipe 31 to the space between partition I l and tube sheet 15, and passes by the tubes 1'7 mainly to section 27.

It will be seen that in. this way the. liquid is caused to traverse successively the pipes of the three sections or divisions 25, 26 and 27, and to free or discharge its vapor in each successively. As a result of this it is found that a materiallv higher degree Off concen' tration is effected than where the entire body of liquid passes at one time through the tubes 17 without any return flow, and is delivered at once and directly from the upper separating chamber. In other words, the condensate accumulating in and flowing from compartment 25 of the topmost separating chamber and strengthened or enriched, is returned to the liquid space or feed chamber below the tubes 17 o'f'the topmost heater, and caused to mingle with the liquid body in said feed chamber; and again, the liquid thus strengthened rises through the tubes to the compartment 26, undergoes separation therein, and in a further strengthened or enriched condition flows back to the common supply at the base of the topmost heating chamber, is then carried upward in the form of vapor to coinpartment 27, where the final separation takes place, and the concentrated condensate in its greatest strength, or enriched to the highest degree, flows from said compart ment through the outlet pipe 82.

The number of heating compartments and separating chambers may be varied at will, three being a convenient and suitable number for general use.

The pipe 33 permits the passage of steam from the lower heating compartn'ient 8 to the upper compartment 13, where itserves to heat the tubes 17 and the liquid passing through them,,and thus to cause a vaporization of their contents or a portion thereof in the same manner as is done in heating con'ipartment 8.

Having thus described my invention what I claim is z-- 1. An eva 'iorator comprising, in conr bination, a plurality of heaters arranged one above another in a common casing, each heater comprising a liquid chamber at its base, a vapor chamber at its top, and tubes connecting said chambers, each liquid chamber being in free and open communication.

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"with the tubes immediately above it; a liquid inlet for the lowermost liquid chamber; separating chambers, one above each heater, the topmost vapor chamber and separating chamber being divided by partitions into separate compartments; a feed pipe extending from the liquid chamber of each heater a-bove'the lowermost, into the liquid space of the separating chamber below it; means for supplying a heating medium to the tubecontaining space of the heaters; vapor-projecting funnels connecting each heater with the separating chamber above it, a separate funnel being provided "for each compartment of the uppermost separating chamber; discharge pipes connecting each compartment of the topmost separating chamber, eX- cept the last compartment, with the liquid chamber next below it; a condensate discharge pipe opening t'rom the last compartment of the topmost separating chamber; and a vapor pipe leading from the uppermost separating chamber, whereby uncondensed vapor may be delivered to a condenser.

2. An evaporator of the character described, comprising a plurality of superposed heaters of tubular construction, each having a liquid supply chamber below and a vapor chamber above, its tubes, the liquid chamber of each heater being in free and open communication throughout its area with the tubes of such heater; separating chambers, one; above each heater; vapor-dis charge funnels connecting each vapor chamber with the separating chamber above it, the topmost vapor and separating chambers of the series being divided by partitions into sepaate compartments, each such compartment except the last communicating by a return pipe with the liquid chamber below it, and said last chamber having a condensate discharge; an inlet for liquid opening into the lowermost liquid chamber; means for supplying a. heating medium to the tubecontaining chambers; and an outlet at the top of the structure for uncondensed vapor.

3. An evaporator of the character described, comprising a plurality of heaters and separating chambers arrangedl in alternation one above another within a casing, each heater having at its top a vapor chamber, and at its base a liquid chamber in free and open communication with the several heater tubes immediately above it, the topmost separating chamber and the -va.por chamber immediately beneath the same being divided into a plurality of compar ments, said compartments except the last being provided with return pipes located Within the heater and serving to return liquid collected in said compartments to the liquid chamber 01 the heater, the last compart-ment of saiot separating chamber being provided with a discharge outlet.

4. An evaporator of the character described, comprising a lower heating compartment provided with tube sheets and connecting tubes; a separating chamber above said heating coinpartn'icnt; a. second healing con'ipart-ment above said separating chant her; and a second separating chamber above the upper heating compartment, said last mentioned separating chamber being divided into a plurality of sections, eaci section except the last having a return pipe for delivering its liquid to a liquid chamliicr or receptacle at the base of the second heating compartment common to the several return pipes.

5. In an eva )orator of the character described, a plurality of heating compartments alternating with a series of overhead separating chambers, the vapor chamber t the final heating chamber and the lower part of the final separating chamber being divided by partitions into a plurality of scetions, each such section except the last having a return pipe for the delivery of the liquid into a single liquid chamber at the base of the heating compartment, common to the several return pipes.

6. An evaporator comprising a plurality of heating compartments each having a liquid chamber at its base and a vapor chamber at its top connected by tubes pass ing through the heating compartment: a steam pipe opening into the base of each heating compartment; a vapor outlet from the upper liquid chamber of each heating compartment; and a separating chamber surrounding the vapor outlet of each heating compartment, the final vapor compartment of the series and: the lower portion ol the final separating chamber being subdivided by partitions into a plurality of sec tions, some of the sections of said separal ing chamber being provided with a return pipe through which liquid t'Ollt'fQlll'ltltGd therein may return to a liquid chan'ibcr common to all said sections, at the base ol the final heat-ing compartment, and another section of said last separating chamber being provided with an outlet for discharge ol the concentrated liquid.

In testimony whereof I have signed in name to this specification.

JAMES CUTHBERT LAlVRENClC Hal lill) 

